There are growing notions among US grain traders that the corn and soybean crops, despite the record late plantings this year, are faring pretty well heading into the critical growing month of August. And the weather forecasts for the next 10 days are not threatening to the crops, with seasonal temperatures but still a bit dry.

The US-China trade front is also getting a bearish read from grain traders.

High-level talks in Shanghai this week have apparently produced no breakthroughs, and President Trump said on Tuesday China cannot be trusted and may stall the trade talks until after the 2020 presidential elections.

Chinese and US trade negotiators will reportedly meet again in the US in September.

Key near-term technical price levels were breached on the downside in corn and soybeans on Tuesday, which has the attention of the chart-based traders, most of whom are now looking to be on the sell side.

The bearish bent in the grain futures markets this week has also emboldened the big speculative "fund" traders to take out fresh short positions in the grain futures markets.

Trade in the US grain markets could be choppy and sideways for the next two weeks, ahead of the all-important Aug. 12 monthly USDA report, at which time the size of the US crops will be updated, as well as revised planted acres for US corn and soybeans.